Process and apparatus for treating yeast



Febo 205 1940. w. P. 'roRRlNG'roN PROCESS AND APPARATUS' FOR TREATIG YEAST Filed May 11,' 1939 Patented Feb.; (j u -in'ria-Nr orifice] Pnoonss annarrm'riisron Tammo msm william P. Torrington, New York, N.' Y., signor to Emnlsions 'Process Corporation, New York,- N. Y., a corporation of Delaware aopuoauon Moy 11, 1939, serial No. 273,078 o claims. (ci. iss-s6) Thisinvention relates to the treatment 'of lyeast and more particularly to a novel method of breaking down yeast cells to release the enzymes contained therein.

5 In the brewing of beer there is obtained as a vby-prirduct, approximately three pounds of yeast for; every barrel of beer' produced, 4which under Y present day practice is only utilized to a very limited extent, and may therefore be considered 10'a` waste product. lIt has long been recognized that such yeast is of value if it could be treated to obtain the highly active liquid yeast contained Within the hemicellulose yeastvcells. This would provide'a yeast concentrate containing the vita- 10 mins present within the yeast cell.

Many methods have been proposed and tried,v

to crack these yeast cells and among them I may mention the use of colloidal mills, ball mills andv various combinations of pressure and vacuum. 20 The vmechanical 'means of cracking yeast have proved very vunsatisfactory because of the minute size of the yeast cells and their elasticity,` making it extremely di'icult to rupture the compara- I tively tough cell walls.

Liquid containingsuch yeast has also been subjected to high pressure and then discharged through anv orice into a vacuum.`

While such methods have worked to avery limited extent, the number of cells broken down has 30 been extremely small.

In the oouoidai machines mwhich attrition-is utilized, the mechanical heat developed is so high that the yeast is killed and the only benet secured is the recovery oi' the vitaminswhich 35 are thermo stable.

The process employing high pressure and dis-v` charge through a nozzle has not operated ei-` ciently ydue to the fact that the liquid within the yeast cells and the surrounding water is 40 practically incompressible so the only action ob-v tained from the discharge through the nozzle is mechanical atomiitation.v

The pri-mary purpose of the present invention is to provide a method. of cracking yeast cells 45 which isentirely practical and which eliminates Withtheforegoingv objects outlined" and with other objects in view'which'will appear as the description proceeds, the 'invention consists in Vthe novel features hereinafter described in deil tail, illustrated in the accompanying drawing and more particularly pointed out in thea'ppended claims.

`In the drawing:

Fig. 1 is a side elevation of the rst portion of the apparatus.

Fig. 1a is a' similarxview of the second portion ofthe apparatus with a part in section lto facilitate illustration.

Referring to the drawing, 2 designates a tank, 3 a pump, 4 a cooler, 5 a dispersion unit or emulsifying mill, 6 a storage ltank forV CO2, 1 a high pressure pump, 8 a tubular type heater, 9 a spray tank, I a vacuum pump, II a CO2 tank, and'I2 a compressor.

The yeast to be treated is lintroduced into the tank 2'through a pipe I3 and in thistank it is mixedwith a suitable nutrient, introduced through the pipe I4. A heating coil I5 is used in this tank to maintain a temperature suitable yto speed' the activation of fermentation.

After the -yeast is activated, it is drawn through thepipe I6 by the pump 3 and is put' undera pressure of about 100 pounds per square inch before it is forced by the pumpthrough a pipe I1 into the cooler 4 where its temperature is reduced t0 about 33 F.

From the cooler; the material is conducted by a pipe I8 to the dispersion mill 5 which is preferably of the type disclosed in the application of M W. Ditto, Serial No. 218,883 filed July `12, 1938. Asit enters the dispersion unit it is mixed with CO2 which is passed from the tank 6 to the inlet of the dispersion mill by means .of a pipe I9. In the mill the SO2 gas` is nely. dispersed in the liquid mass and the mixture is` discharged from the mill through a pipe 20 that conveys the same to the high pressure pump 1 Iwhich raises the pressure of the mixture to a pressure of the order of 3,000 pounds per square inch, before the mixture travels through a .pipe e ZI into one end of the tubular heater 8. In passiugthrough the heater the material is raised in temperature 'to approximately 120 F. by any suitable heating medium introduced into the heater at 22 and ydischargedat 23.

lifter heating, the material travels through Aa pipe' 24 terminating in a sprayhead 25 yar-4 .ranged in. the' tank 9. As the interior of the tank is maintaiuedunder subatmospheric pressure, the CO2 will bereleased from the mixture and will be withdrawn by the vacuum pump I0 through a pipe 26 v'which forces suchvgas through a pipe '2l into Athe tank I l. It 'is withdrawn from the 'latter by means ofthe compressor. I2, which places it under apressure in excess or 100 pounds per square inch so that itmay be returned to start formation of alcohol and CO2.

activity has continued until-all the yeast is acthe tank 8 through the pipe 28 and be vpassed from the tank 6 into the dispersion unit 5.

From the tank 9 the yeast may be withdrawn through a. pipe 29 and passed. to filters, evaporators, etc.

In one method of operation, I take the waste yeast from a beer-making process or the like, and thoroughly wash it to separate the foreign matter, using antiseptic solution if necessary to kill bacteria. Any suitable bactericide maybe used for this purpose, for example, ammonium Apersulfate, one pound of which may be used for each 75 pounds of yeast to be washed, along with about 7% gallons of cold water. The yeast is usually allowed to stand in this solution overnight, aiter which it is decanted. Ordinarily the c yeast is allowed to stand after washing, and after decanting, the watery mass will be averythick mass consisting of about 80% water and 20% dry yeast, Water is added to this mass so that the percentage of dry yeast is reduced to approximately 10% before treatment is started.

The temperature of this watery mass is brought to about 55 F. and then in the tank 2 (or before entering this tank) it is mixed with sufficient sterile wort to act as anutrient and cause the yeast cells to immediately swell and When this tive, I pumpY this yeasty liquid by the pump I through the cooler I under a pressure oi' about 100 pounds per squarerinch, and introduce it under this pressure into the dispersion unit-at a temperature of about' 32 F. CO2 is introduced into the unit along with the yeast liquor and due to the action of the mill, is finely dispersed throughout the liquid. In the mill the temperature oi' the mass is maintained at approximately 32v F. f

'I'he carbonated and activated yeast solution is then raised in pressure, ranging between 1000 and 3000 pounds per square inch, and afterwards:

its temperature is brought up to abciut 120 F.

which issutilcient to completely convert the vcarbonic acid to CO2.' The mixture is tlie'ri'dis'- charged through the spray head 25 into the tank 9 which is under atmospheric pressure or vacuum.` Ihe action is three-fold. The -iinely atomized gas containedin the liquid being released from relatively high superatmospheric' pressure to a much lower pressure, causes a very violent "mechanical atomization; a certain portionoi theYV C02 `due tothe high pressure has penetrated the yeast cells and with the CO2 from the action within the yeast cells themselves, by the addition of a nutrient, causes the yeast cells to be rup- -tured, due to the explosive expansion of the gas contained therein.A The CO2 is then pumped from the top of the discharge chamber I i and can be recycled. c

vfrhe uquid containing the .cracked yeast is then illtered to eliminatel the solid matter which consists of hemicellulose yeast eells and is then concentrated undervacuum to a desired degree.

The reaction is4 further aided by the weakeningv cfthe cells due to the activity that takes place when i'ood is supplied to-'dormant yeast.

From the foregoing it is believed that my.

method of procedure and novel apparatus may be clearlyunderstood by those skilled in the art, and I am aware that changes may be made in the speciilc steps oi the method and 'in the details o! the apparatus without departing from the spirit of the invention as expressed in the claims.

2,190,689 what I claim and desire tc secure by letters Patent is:

1. In a method of .the character described,

maintaining yeast in contact with a nutrient forA a. sufficient period of time and at a suitable temperature to cause the yeast cells to swell and form gas within themselves, subjecting such material high superatmospheric pressure and increasing the temperature of the solution to a temperature of the order of 120 F., then suddenly releasing the pressure on the solution and thereby releasing the CO2 and rupturing the yeast cells, and subsequently separating the CO2 from said solution. Y-

3. In a method ofthe character described, subjecting an aqueous solution of active yeast to dispersionin combination with 0,02 under superatmospherlc pressure, increasing'thepressure oi' the resulting mixture to a pressure between approximately 1000 and 3000 ppunds per square inch and raising the temperature of the mixture to a temperature otxthe order of 120 F., then suddenly releasing such pressure whereby CO2 is released from the mixture and the yeast cells are cracked, and then separating the C02 from the yeasty mass.

4. In a method of the character described, mixing yeast with a' nutrient and thereby producing yeast in aqueous solution, placing said solution under superatrnospheric pressure and iinely dispersing CO: in the solution while the latter is maintained at'atemperature of substantially 32 F., then increasing the pressure of the mixture to a pressure above 1000 pounds per square inch and raising the temperature of the mixture to the order of about 120 F., then suddenly releasing the pressure on the mixture y and thereby releasing the CO: from the mixture and cracking lthe yeast cells, and nally separating the CO: from the remaining yeasty solution. 5. In a method of the character described, activating a yeasty solution and then placing the solutionl under a superatmospheric pressure of the order o i" 100 pounds per square inch and under a temperatureof about 32?-F., then suddenly dispersing CO: throughout the solution while it is maintained under approximately said pressure and temperature, then increasing the pressure andv temperature ofthe resulting mixture, and subsequently discharging the mixture into a chamber maintained under substantially atmospheric pressure and thereby releasing the CO2 and cracking the yeast cells.

`6. In a method of the character described.l ac-i tivating a yeasty solution and then placing the solution under a superatmospheric pressure of the order oi' 100 pounds per square inch and under a temperature oi' about 32 F., then suddenly dispersing 'CO1 throughout the solution while it is maintainednnder approximately said pressure 2 and temperature, then increasingd the pressure and temperature of thei resulting mixture, subsequently discharging the mixture into a chamber maintained under substantially atmospheric pressure and thereby releasing the CO: and 75 l i temperature until all the yeast is activated, then placing the resulting aqueous mass under superatmospheric j pressure and passing the same through a dispersion chamber, ilnely dispersing CO throughout the mass in said chamber while the mass is maintained at a temperature of about 32 F., then. increasing the superatmospheric pressure on the resulting mixture and raising the temperature of the mixture to about 120 F.,

then releasing the pressure and introducing the mass into a chamber maintained under substantially atmospheric pressure whereby the yeast cells are cracked andthe C02l is released, and

nally separating the CO2 from the mass.

8. An apparatus o! the character described,

comprising means for placing an aqueous solution of active yeast under superatmospheric pressure and a relatively low temperature, a dispersion mill, means for introducing the solution into said mill, a CO2 storage tank, a conduit for conveying CO2 from saidtank to the dispersion mill,

a highpressure pump, a .conduit for conveying a carbonated mixture of such 4solution fromthe dispersion mill to the high pressure pump,.a conduit f or conveying the mixture from the pump and terminating' in a spray head, a heater interposed in said conduit, .a tank in which the spray head is arranged, means for discharging gas from the -upper portion oi the tank, and means for discharging a liquid mass from the lower portion of the tank. v .l .v

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